Correct make of bike, at least 
Is it a headstock lock nut tool for a CBR600RR?
I’m afraid not…
Total guess … It’s a castle or castellated nut spanner so, maybe for a SSSA locking nut? VFR800?
No. One thing I did notice when having an idle Google was how much manufacturing has come on. I bought this to do a specific job in 1976, and they’re still available. The ones now make this look like something I knocked up in the shed. Probably not that different on price either, I can’t remember TBH. Been to bed since then… 
Here’s a massive clue then
Clutch locknut tool for CB400 blue?
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Bang on, right down to the colour. I hadn’t realised the superiority of red bikes back then. It did look pretty sharp in blue to be fair. Loved it 
It popped a seal which required whipping out the lump to split the crankcases. I discovered the leak when it oiled my rear tyre and put me on my earhole one day
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Yes!!! Those are the cams for use in a mitre box cutter, for holding your wood in place!! The cam allows you to tighten up against the wood…
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Aha! I have one of those! Bought it years ago and completely forgot those were bits to go with it. THank you for solving the mystery!
Mine must have been a real cheapo version as it didn’t offer such an option
I expect you were to use your thumb, like mine does